Biphasic cellular and tissue response of rat lungs after eight-day aerosol exposure to the silicon dioxide cristobalite

• Published in: The American journal of pathology Vol. 134; no. 6; pp. 1243 - 1251
• Main Authors: Absher, MP, Trombley, L, Hemenway, DR, Mickey, RM, Leslie, KO
• Format: Journal Article
• Language: English
• Published: Bethesda, MD ASIP 01.06.1989; American Society for Investigative Pathology
• Subjects: Aerosols; Animals; Biological and medical sciences; Bronchoalveolar Lavage Fluid - cytology; Chemical and industrial products toxicology. Toxic occupational diseases; Hydroxyproline - analysis; Inflammation - pathology; Inflammation - physiopathology; Inorganic dusts (pneumoconiosises) and organic dusts (byssinosis etc.); Lung - analysis; Lung - cytology; Lung - physiology; Lymphocytes - cytology; Male; Medical sciences; Organ Size; Proteins - analysis; Rats; Rats, Inbred F344; Silicon - pharmacology; Silicon Dioxide; Time Factors; Toxicology; Pneumoconiosis; Experimental disease
• ISSN: 0002-9440; 1525-2191

Cristobalite is a crystalline silicon dioxide that elicits pulmonary inflammation and fibrosis in humans and experimental animals. Exposure of rats to aerosols of respirable cristobalite for 8 days led to a rapid influx of neutrophils and macrophages into alveolar and tissue compartments of the lung followed by a more gradual accumulation of T lymphocytes. This inflammatory response persisted throughout 52 weeks after the end of the exposure. For some variables studied there appeared to be a cyclical nature to the response. Statistical analysis of alveolar cell populations and lung tissue weight, protein, and hydroxyproline showed significant time-dependent fluctuations. Histologic analysis revealed a progressive deposition of collagen and type II cell hyperplasia centered on airways, however, there appeared to be some correlation between fluctuations in alveolar cell populations and overall tissue pathology. The observed cellular and biochemical fluctuations and the persistence of the inflammatory response may be due to the presence of silica in the lung, which serves as a source of repetitive stimulation of lung cells.